char* search(char* s,char* t) {
    char *p1,*p2,*p3,*ret = NULL;
    for (p1 = s;*p1!='\0';p1++){
        if(*p1==*t){
            p2 = t;p3 = p1;
            while(*p1&&*p1==*p2){
                p1++;
                p2++;
            }
            if(*p2=='\0'){
                ret = p3;
                break;
            }
        }
    }
    return ret;
}
